This is a summary of a lecture given by David Keith. The original video of the lecture, as well as the transcript can be viewed here: http://blog.ted.com/2007/11/13/david_keith/
This lecture was given by David Keith, an Environmental Scientist, back in 2007. He suggests research into the idea of injecting a huge cloud of particles into the atmosphere in order to deflect sunlight and heat. Apparently, this idea was first suggested in the 1950's (yes, we scientists have actually been aware of rising CO2 levels and the implication that it had for raising overall global temperature for much longer than I thought!), but this idea has never been seriously studied in depth.
David Keith suggests that this is a fringe solution. It has not been given any serious funding for research. But he says that the cost needed for research would be small (as in less than the US is currently spending on defense) and if found to be a viable solution, the cost of implementing such a plan would be very cheap as well.
Apparently, this solution would be akin to what happens on a global level when there is a large volcanic eruption and the ash fills the atmosphere in a cloud that blocks out the sun for a while in some areas of the world. He references Mount Pinatubo in the early 90s and the documented effect of global cooling that happened then. Apparently, this has happened many times in history when volcanoes erupt.
Keith suggests that this could at least buy us some time to change some of our habits. He states that the problem with simply making drastic cuts to emissions (which we, on a global level, have really failed to do anyway) is that the effects of those cuts take time. It will be several years before the cuts that we make now will be reflected in the atmosphere in terms of reduced CO2. However, Keith suggests that a large cloud, similar to that of the cloud of volcanic ash that would be in the atmosphere after a large eruption, would have an immediate cooling effect on a global level. And since we are seeing levels of CO2 and warming much more drastic than scientists have been predicting, maybe such an immediate solution is what we need to buy us a little time to make the changes, like emission cuts, that will take longer to have an effect.
Of course, there is a moral dilemma here. First, if the cloud solution does have an immediate and positive effect, there is a risk that people will not want to make the further necessary lifestyle changes, like emissions cuts, that are necessary to try to curb global warming. Without such an immediate threat, will people forget that there is a threat at all? Second, we would have to have strict rules about when this is employed and who gets to decide that? If one country decides that they want to do it, is that OK? What kind of global governing body will be in place to decide when this technology would be used. Because for better or for worse, this technology will have an effect on the entire planet.
This was posted 2 years ago and I wonder if any research money has been given to such an idea. It seems like it has some merit, but it also seems very scary. It could have drastic effects, for the positive and for the negative. As a species, human beings don't exactly have the best track record for manufacturing ways out of environmental disasters. Without serious research, I could see the use of this idea causing serious negative consequences that we would have no idea how to solve.